From Phoebe carrying triplets for her brother and his wife to Chandler and Monica adopting newborn twins (viaHello!
Born near the end of the first season, Ben was Ross’s son with ex-wife Carol.
One of those theories is pretty dark, and likely to change how you see some of the characters.

Ross’s behavior got more erratic as the series continued
AReddituser called D.F.
In the timeline of events, Ross starts acting more and more erratic.
The following season, he even tries to kiss his cousin.

Either way, Ross doesn’t come out of this too well.
It’s true that Ross might still have seen Ben off-screen, we just don’t know.
Perhaps it’s only fair that we give him the benefit of the doubt.