Is it a red flag if all a guys children turned out messed up

I'm 34 and am seeing this guy who just turned 53. Things are weird because this already started out with him not being very honest. He didn't flat out lie to me but he left a lot out. I thought he only had one kid. His son who is 20 and currently in college and already finished flight school. He works a really good job and is making really good money for a 20 year old. Him and the guy I'm seeing wife divorced a year ago after 31 years of marriage. He started saying how he would really like to have more kid. I have no kids but he really wants more. Again I thought he only had one kid. Come to find out he has 8! All with his ex wife. He didn't tell me about them because all his other kids are either on drugs, in recovery from drugs, or in prison. Some of them are getting their life together, two of his sons and one of his daughters are sober now and doing their best to be the best parents they can be. While one daughter is still on drugs and two more daughters and one son are in prison. I think a child can have a good life and still go down a bad bath but how do 7 out of 8 kids turn out messed up and it have NOTHING to do with the parenting at all. In fact the ONE son who is doing well wasn't even raised by him and his wife. He was taken away at a young age and adopted out. They actually don't even really have a relationship so for the last 5 months he's been talking about his youngest son and how amazing he's doing and showing me his pictures when neither him or his ex wife are really involved with him. And now he's telling me he wants more kids and wants to get me pregnant. I don't think he's very parent material if 99 percent of his children turned out like that. It doesn't sound like him or his ex wife were very good parents. And going 5 months pretending you didn't have other kids and you have such a great relationship with your youngest son is weird.