In Season 3, episode 11, Burt is at the doctor’s office finding out that Mary is pregnant and tells the doctor he has 3 kids before. There was Peter and Chuck. Who was the third kid??

Bob?

Burt did say he was the one who gave Bob to Chuck so I guess Bob was adopted. :crazy::crazy:

Maybe they had plans to bring on another child of Burt's but just never did. I seem to remember a line from Jessica once about her having FOUR kids, but we only ever met Corinne, Billy and Eunice.