We’ve probably lost our ability to be shocked by allegations of sexual abuse that turn out to be true.

The American statistics are staggering — one our of four girls are molested before they turn 18, one out of six boys.

So the revelations, when they come in “Rewind,” don’t have the jolt that they did in “Capturing the Friedmans,” or even in the mini series about the widely-publicized crimes of R. Kelly and Michael Jackson.

But this film, directed by one of the victims in a family torn apart by generations of abuse, gets to you from the haunted home video images of a seriously unhappy little boy.

“I don’t want to curse my parents,” little Sasha, who looks to be nine or ten, pouts to the camera. “I don’t want to HATE my parents!”

But Sasha, a once-promising child identified as “gifted,” suddenly acting-out, lashing out, hurting his little sister Bekah, has gone through something. “Rewind” uses those home movies, hours and hours of them shot by his PBS videographer father Henry, to piece together the unhappy events that flipped that switch in Sasha.

As Henry remembers in Sasha’s film, “You didn’t film things that were bad” in your home movies. “You filmed celebrations, happy occasions.” You could only find the unhappiness and the sinister actions creating it “in the background.”

The adult Sasha interviews his parents, mother Jacqui, a graphic designer, and father Henry and paints a portrait of suburban dysfunction that prefigured the tragedy that hangs over Sasha and little sister Bekah’s lives.

Jacqui complains that Henry was tuned out — showing up very late to her Sasha’s premature birth because “he was out buying a video camera.” Henry’s obsession “became a wall tween my husband and my family.”

Jacqui acted-out against Henry’s obsessive video recording, bowing out of the shot. We also hear her cursing her little boy in one instance.

The “mystery” is set up as Henry was so intent on documenting everything, he’s either some sort of pervert, or he was blind to what was happening to their very young kids at the hands of someone the children know.

That’s the MO of pedophiles. They prey on children they know, have access to, family members included. Henry got LOTS of video of the criminals.

“Rewind” has Jacqui take the role of the parent who catches on, who questions her son, questions the first doctor they take him to with signs of sexual injury. Talked out of “reporting” that by her pediatrician, she tries to draw Sasha out. And failing to get through, she takes him to a therapist.

Dr. Herbert Lustig kept the kid’s files, and we see them as Sasha revisits the man who who told him, “If you can’t describe what happened, can you draw it?”

“Rewind” is a textbook case of what happened, how it played-out within a still-callous legal system (powerful people get involved), the injustice money can buy perpetrators, and how the molested often turn into molesters themselves.

There’s nothing wrenching on screen, no grim confrontations with the criminals, just sobering memories from guilt-ridden parents, members of the legal system remembering the case and helping recreate Sasha’s gutsy, blunt tweenage to teenage testimony.

The revelations come relatively early, and the trauma of a child having to go through what any accuser has to endure — endless repetitions and re-interrogations (traumatic, and case-damaging in many instances) — becomes the focus of the film’s final third. Sasha, keeping most of the focus on himself, lets that become the movie.

“Rewind” arrives at a point in time where we’re beyond being shocked, where we despair that even the heroes aren’t heroic enough or quick enough to act, and real justice for the victims seems an illusion.

But films like this are important reminders that we’re not doing enough, that the social stigma that prevents us from acknowledging the extent of the problem is still there, and that no amount of brushing aside, “normalizing” or letting off with probation the sexual predators among us should let us forget how horrific and traumatic these crimes remain.

MPAA Rating: Unrated, graphically described sexual abuse subject matter, profanity

Credits: Directed by Sasha Neulinger.  A Grizzly Films/PBS “Independent Lens” release.

Running time: 1:26