Gosh, sorry this has been such a difficult and complex situation for these kids. Why were the kids removed? I'm just curious. To lose custody of your children, there must have been some serious offenses.
Anyway,, yes. It is possible that he has seen something or been exposed to something. I'd let his caseworker know. good luck
It is possible that the violent home environment he was removed from, or the interim placement, could have exposed him to something. Or are you concerned because he is in the care of someone who is gay? Child molesters tend to be straight more often than gay (though the gay ones get much more angry attention), and what he is doing is heterosexually focused, I guess you could call it. I'd question the place where he was cared for when not with his siblings, and also would wonder about the actions of the oldest child, who witnessed the abuse of his mother for a long time.
I agree that this is a very complicated situation that no child should have to endure. There could be a whole host of reasons why Micheal engaged in this behavior twice. For the emotional stability of all the kids including Micheal, it would be very appropriate for them to be actively engaged with their own mental health therapists. Among other significant issues, these kids obviously have separation/loss issues. It would be in this context that the answer to your question could be found.