Where did you find that misinformation? Yes almost all of the Miller's are insane but they won't go as far as r*ping their own dad who gave birth to them. The eldest brother is distant to their Omega dad, in fact he even calls his dad formally "Mr. Niles". He's also uninterested in their family affairs just like Chase.
But I'd say their youngest was the one in the most dangerous position since he's close with all of his siblings and he's the only and first Omega child in the family, Ashley their father is overprotective on the youngest, he was even worried that he would accidentally get r*ped by his siblings, so when his siblings visit him they always have to go through Ashley first.
His siblings always surrounded him when he manifested at the early age of 8.

Is it true that the Miller children tried to their own mother? Like no way..... Chase would never, and Grayson (maybe), how about their oldest brother? I know the youngest son is an omega so fat chance.