A jury convicted LaStarza Mannie of sexually assaulting his 12-year-old niece, and sentenced him to 35 years’ imprisonment. On appeal, Mannie complains that evidence of his having sexually assaulted his niece on a prior occasion should not have been admitted, that the evidence is insufficient to support his conviction, and that the statutory parole law instruction should not have been given to the jury. We overrule Mannie’s three points of error and affirm the conviction.
To see whether evidence is sufficient for conviction, we must view it in the light most favorable to the verdict and decide whether any rational trier of fact could find the essential elements of the crime beyond a reasonable doubt. Sutherlin v. State, 682 S.W.2d 546, 548-549 (Tex.Crim.App.1984). We therefore turn our focus upon the evidence in support of the verdict.
At the time of trial in 1986, Mannie was 35 years old, divorced with no children. Before the events of Christmas-time 1985 which concern us here, Mannie had, on occasion, lived in the home of his brother, who was married with five children. Even *753when he was not living in his brother’s home, Mannie often stayed with the children when their parents were away. M_, Mannie’s niece, the oldest of the children, was a twelve-year-old seventh-grader during the period of time important to this case.
M_testified that one evening between Christmas 1985 and New Year’s Day, her father and Uncle Mannie returned home from fishing about 10:00 p.m. M_ remembered that she had gone to bed about an hour earlier but awakened when she heard her father’s car start up and pull out of the driveway. She would later learn that her father and mother left to go to the store, but that night she just fell asleep again after hearing the car leave.
A few minutes later, M_ was again awakened, this time by her uncle Mannie pulling her out of bed. She recalled that he took her, half asleep, into the den and laid her on the floor between the couch and fireplace, face up, dressed only in her panties and mother’s cotton nightgown. By the dining room light she could see her uncle Mannie, wearing pants, a jacket and a sweater, crouch over her and pull down his pants. Then, M_ testified, while her brothers and sisters slept, Mannie raped her. Mannie stayed on top of her for what seemed like a long time, M_said, moving up and down, hurting her, saying nothing. Suddenly, as M_’s parents’ car drove up, Mannie stopped, got off her, pulled his pants up, and in a rough voice told her to tell no one what had happened. M_got up and returned to bed.
M_ testified that she waited in bed until her mother was asleep and her father had left to take Mannie home, and then went to the bathroom and washed herself with a wet wash cloth and soap. She testified that she did not see anything wet on her but she cleaned up because there might have been, as there had been before, the first time Mannie assaulted her.
Over Mannie’s objection, M_testified that Mannie had raped her once before, about two months earlier, when Mannie was staying with her and her brothers and sisters while her parents were out of town. That time, she said, she was in her room doing her homework when Mannie came in and told her to go clean up the bathroom. She testified that when she went to the bathroom to do as she had been told, Man-nie came in the bathroom with her, shut the door, and pulled down his pants. Then, she stated, Mannie laid her face up on the floor, pulled down her pants and underwear, and raped her, moving up and down. M_testified that Mannie hurt her, and that when he got up she noticed “wet stuff” on her leg. Mannie pulled his pants up and left. M_cleaned up with a wet cloth and soap, and then returned to her room.
M_testified that at first she told no one about the earlier incident because she was afraid. She said she was bothered at school and at home and thought about what had happened, but kept it inside. After the later incident she was also afraid to tell anyone what had happened, partly because Mannie had warned her in a rough voice not to, and partly because people would think bad of her. M_ testified that she felt embarrassed and unclean.
M_ said her conscience continued to bother her until she decided she had to tell someone what had happened. On February 5, 1986, during her lunch break at school, she went to her guidance counsel- or’s office, closed the door, and said she needed to talk. The counselor testified that M_was crying and had difficulty talking, but managed to tell about both times Mannie had raped her. The counsel- or called her mother to take her home, and her mother called the police.
The next day M_and her mother saw Dr. Julie Fryberg at Children’s Medical Center. Dr. Fryberg examined M_and testified at trial that she had a torn hymen, consistent with penetration of her vagina by a male sexual organ. Dr. Fryberg testified that during the examination M— was cooperative but withdrawn, “very appropriate for having experienced [a sexual] assault.”
M_ testified that Mannie had stayed with her and her brothers and sisters many times and had never been ugly to any of *754them. She said Mannie had been good to her and that she was not afraid of him. M_testified that she goes to church and knows the difference between the truth and a lie. She stated that she watched television and read newspapers, but that she had never read about child abuse. She testified that she did not make up the charge against Mannie.
M_’s father testified that these circumstances had been a “very heartrending and emotional time”. He remembered that Mannie had stayed with his children while he and his wife had traveled to Tennessee. He also stated that he and Mannie had probably gone fishing in December, although he simply could not recall one way or the other having done so between Christmas and New Year’s Day. M_’s father acknowledged that he testified before the grand jury that he believed his daughter over his brother, but that his daughter did not appear to have been emotionally hurt.
One of Mannie’s best friends, Bob Steele, testified that Mannie stayed with him and his wife at their trailer home all weekend after Christmas. Most of the time, Steele said, he and Mannie just laid around and watched cartoons on television. He was pretty sure, he said, that Mannie did not go fishing with his brother that weekend. But Steele’s testimony, it is fair to say, was rather ambiguous at best, as the following excerpts show:
Q Do you recall what you did on Saturday [after Christmas]?
A Mainly laid around.
Q All right. Did you go with LaStar-za Mannie over to his brother’s house?
A I don’t think so, no.
Q Did you go at any time around the Christmas holidays?
A No.
Q And during the Christmas holidays, during that vacation time, Les Mannie was with you at least that whole weekend?
A Yes.
Q And the — Les was there that Saturday?
A Yes, uh-huh.
Q And he never left the house?
A That night, yes.
Q I’m talking about Saturday.
A No.
Q He never left the house?
A No.
Q You just stayed there and watched TV the whole time?
A Yeah....
Q So you watched cartoons all day long?
A Yes.
Q So, you watched every move that he made?
A Every move?
Q Yeah.
A Well, he didn’t leave the house.
Q You’re positive about that?
A Yeah.
Q Didn’t leave the house over what period of time? I’m talking about from, let’s say, the Friday that you’re talking about until — Well, what day was Christmas on?
A Tuesday, I believe. [Christmas was actually on Wednesday in 1985.]
Q Okay. So, from what period to what period of time are you saying that Les never left the house?
A You mean leave the house to go out, stay two, three hours? Is that what you’re saying?
Q I’m just talking about leave the house.
A No, he didn’t leave the house, no.
Q Over what period of time, two weeks, three weeks? Beginning when and ending when?
A Okay. I say that next month in January he probably left the house that second week in January. He might have went fishing with his brother, something like that.
*755Q Okay. So, we’re talking from what time to the second week in January did Les Mannie never leave the house?
A What specific time? Is that what you’re saying?
Q I’m just trying to get a ball park. From what time to what time? From what time to — what period of time from here, point A, to point B, second week in January, did — are you saying that Les Mannie never left your house?
A That’s a difficult question. I can tell you this: That Saturday morning he was there; Sunday morning he was there; Monday morning I believe I took him to work.
The only night between Christmas and New Year’s Day that Steele said he was with Mannie was the Friday night after Christmas. M_did not recall what day of the week it was that Mannie assaulted her. Steele’s memory was vague, despite the fact that Mannie had called Steele from jail to ask him to remember what went on the latter part of that December. “Really,” he told the jury in the courtroom, “I didn’t remember until I was sitting outside out there.”
Finally, Mannie himself testified. He admitted that he had stayed with M_and her brothers and sisters when their parents were in Tennessee, and that he often went fishing with his brother, M_’s father. But Mannie denied that he had gone fishing with M_’s father anytime between Christmas 1985 and New Year’s Day, and that he had ever sexually assaulted M_ His only explanation of his whereabouts from Christmas to New Year’s Day was: “I was over to Bob Steele’s house, where I was living.” Mannie acknowledged that at the time he testified he was on parole from a sentence of eight years’ imprisonment in the penitentiary for two felony convictions of possession and delivery of heroin.
Taking Mannie’s complaints on appeal in logical order, the reverse order in which he presents them, we first address Mannie’s argument that the trial court erred in admitting evidence of an extraneous offense, namely, M_’s testimony about the first time Mannie raped her about two months before the offense with which he was charged.
Generally, evidence of an extraneous offense is inadmissible unless it is relevant to a material issue, and its probative value outweighs the danger of unfair prejudice. Williams v. State, 662 S.W.2d 344, 346 (Tex.Crim.App.1984). In a case of sexual assault by an adult against a minor, however, evidence of prior sexual offenses by the adult against the minor may be admissible to “aid the jury in properly evaluating the ‘inherently questionable testimony of a minor against an adult responsible for his welfare’ or in a position of authority or control over the minor.” Boutwell v. State, 719 S.W.2d 164, 178-179 (Tex.Crim.App.1985).
Cases involving sexual assault of children are not an exception to the general rule of the inadmissibility of extraneous offenses, as they are sometimes mischarac-terized, but only a special application of the rule. The decision to admit or exclude evidence of extraneous offenses in any case, regardless of the charge, can be made only after logical analysis and never automatically or mechanistically. Id. at 172.
Every case must be examined on its own facts, strengths, and weaknesses to determine whether the extraneous transaction is relevant to a material issue, and whether the relevancy value outweighs the prejudicial potential.
Id. at 174.
Broadly speaking, the potential prejudice to the defendant is that he will be tried for a crime with which he is not charged, or as a person predisposed toward criminal conduct generally without regard to the particular offense for which he is indicted. Id. Against such possible prejudice the probative value of the evidence must be weighed.
In this case, evidence of Mannie’s prior sexual assault on M_was relevant to place the charged offense in the context of the relationship between Mannie and his niece. Boutwell expressly acknowledged the propriety of admitting evidence
of acts which occurred between the minor complainant and the defendant so as *756to explain the charged act and view such an unnatural act in light of the relationship of the parties as well as to make a child’s accusation more plausible. A jury would otherwise hear essentially an incomplete version of the charged offense, as though it had occurred in a vacuum as a one-time act. Such evidence from a child, standing alone, might be considered implausible or incredible.
Id. at 175.
The jury’s decision in this case, as in many cases involving sexual assault of a child, came down to one issue: whether to believe the complainant or the defendant. It is, of course, not unusual for a case to turn on the credibility of witnesses. What is unusual about cases involving sexual assault of a child is that the very nature of the allegation tends to make the complainant’s testimony implausible. M_’s credibility, like that of complainants in many such cases, was in doubt before she opened her mouth simply because of the nature of her testimony: she was accusing her father’s brother of the unnatural and despicable act of having sexual intercourse with his twelve-year-old niece. Such “inherently questionable testimony”, as the court of criminal appeals characterized it in Bout-well, placed M_at a disadvantage in testifying against her uncle. To overcome this inherent disadvantage, it was important to show that the charged offense did not occur “in a vacuum as a one-time act.” Id.; see Smith v. State, 719 S.W.2d 402 (Tex.App.—Houston [1st Dist.] 1986).
This is especially crucial when, as here, the defendant had it within his power to deny corroboration to his victim’s charge. Mannie could choose to rape his niece, not in public or in front of witnesses, but in secret. He could pick an occasion — in M_’s own home with her parents gone for only a short while — when it was even more unlikely that he would attempt such a thing. He could use his relationship of authority over M_to intimidate her into a silence that allowed all tangible evidence to dissolve and with every passing day cast a darker shadow of doubt over her eventual accusation. The only “corroboration” left M_was to explain the whole of her relationship with Mannie, both good and bad, which she did. See Boutwell, 719 S.W.2d at 178.
The possibility that the jury convicted Mannie for the prior extraneous offense rather than the subsequent charged offense is remote. The only significant difference in the two incidents was that Man-nie admitted being present in M_’s home at the time of the first incident but denied being present at the time of the second incident. Thus, the issue of opportunity raised in the charged offense was not present in the extraneous offense. Nevertheless, the factuality of both incidents rested squarely upon M_’s credibility, and her testimony regarding the extraneous offense was not significantly more believable than her testimony regarding the charged offense, if it was more believable at all.
The possibility that the jury convicted Mannie as an inveterate scoundrel based on M_’s testimony of the extraneous offense is likewise remote. Had there been evidence of chronic sexual abuse, as is not uncommon in such cases, or of other offenses completely unrelated, perhaps a jury might have been persuaded to convict Man-nie as a confirmed criminal while harboring reasonable doubts that he actually committed the charged offense. The possibility that the jury would be inflamed over evidence of one recent extraneous offense of like kind, at least in the circumstances of this case, is not great.
In this case, M — ’s testimony about the other time Mannie raped her is peculiarly relevant to the jury’s main concern, her credibility.1 Mannie’s attorney *757put the crucial question to M_directly: hadn’t she made the whole thing up? In this day and time, sexual encounters and stories of sexual abuse are tragically commonplace enough in a twelve-year-old’s world to stimulate an active imagination and provide the details for a credible tale. Such knowledge, however, does not supply a seventh grader with the skill to fabricate a lie that can withstand the assay of cross-examination and convince twelve adults beyond a reasonable doubt. As difficult as it is to improvise one plausible story, it is doubly difficult to devise two. If M_’s testimony about the extraneous offense had been dubious, her otherwise credible testimony about the charged offense would likewise have been subject to question. However, M_’s realistic descriptions of both incidents helped establish her credibility. If M_were imagining things against her uncle Mannie, then why more than one incident, why not more than two, and why stories with different details? Could M_ tell two complete stories of sexual abuse by her father’s brother in the unfamiliar crucible of the courtroom that could persuade twelve jurors beyond a reasonable doubt and, importantly, her own skeptical father? The extraneous offense evidence was relevant to answer such questions and to enable the jury to judge credibility.
Following Boutwell, we reaffirm that evidence of an extraneous offense is not admissible in every case involving the sexual assault of a child. We have carefully examined this case, as we are required to do, and conclude that here the probative value of the extraneous evidence outweighed any possibility of prejudice. The trial court did not err in admitting the evidence.2
Turning to the issue of whether the evidence is sufficient for conviction, we emphasize that we cannot judge the credibility of witnesses or the weight to be given their testimony, nor may we resolve conflicts in the evidence. Those matters are for the jury alone. Esquivel v. State, 506 S.W.2d 613, 615 (Tex.Crim.App.1974). Only the jury could contrast M_'s demeanor with Mannie’s. Only the jury could judge whether the details of M_’s account of what happened and the manner in which she related them were too real and too coherent to have been fabricated by a twelve-year-old, nervous about testifying for the first time in court, who, freely admitting that her uncle Mannie had been good to her, had no apparent motive to lie. Only the jury could decide whether the testimony of Mannie, a twice convicted felon on parole, and his best friend, Steele, attempting to provide Mannie with an alibi, was too vague and inconclusive to be believed. Only the jury could decide to believe the victim over her assailant. It is *758not for us to decide whether Mannie was guilty; that decision is the jury’s exclusive prerogative, to be made without reasonable doubt. Our duty is but to pronounce whether they could have made their decision rationally. We conclude that they well could have. The evidence is sufficient to support Mannie’s conviction.
Finally, we hold, based upon our prior decisions, that the trial court did not err in giving the jury the parole law instructions required by article 37.07, section 4, of the Texas Code of Criminal Procedure. Rose v. State, 724 S.W.2d 832 (Tex.App.—Dallas 1986, pet. granted); Joslin v. State, 722 S.W.2d 725 (Tex.App.—Dallas 1986, pet. granted).
The judgment of the trial court is accordingly affirmed.
THOMAS, J., concurs.