Thanks for the clarification on his children. I was thinking in terms of younger children, not adults.
Being clingy indicates insecurity. Personally I can't engage with someone like that.
I briefly dated a guy who had been sober 2 years, and although he wasn't physically clingy, he was emotionally clingy. That's a huge turnoff for me.
It got to the point where he was calling every day, sometimes more than once, and I eventually stopped answering the phone. I had asked him not to call every day, and apparently he wasn't going to listen.
He ended up drinking again, and that was the end of that. He's been out there drinking for over 3 years now.