Please don't quote me, I'll likely DD.
My son is nearly 17. I had him in high school, and his dad and I had broken up by the time I delivered. His dad moved away, and has been largely absent from his life - has gone up to four years at a time without a letter, phone call, or visit. The last time either I or my son heard from him was three years ago. Nobody from bio dad's family has been in contact with us for years. My son intends to take DH's last name when he turns 18 next year, and considers DH to be his father.
I found out through distant acquaintances that bio dad is expecting a child soon. I'm not sure if I should tell my son - on one hand, the baby would be a blood relative, but I don't really see any benefit to sharing the news with my son. Any thoughts?
UPDATE: I mentioned the situation to my son earlier today. He thought about it for a moment, then asked "do you think I can assume my baby shower invite was lost in the mail?" with a healthy dose of sarcasm. Then he went back to shopping online for car accessories. He's extremely well adjusted, both to the absentee father situation and in general, so I think he'll be fine. And I'm off the hook.