".. and the other two kids."

Sollozzo says that to Tom. What other two kids? Well, Fredo and Michael. What about Connie?

Of course, Connie would have been valueless in the business. However, it might also be a comment on the general perception of women during that era.

"Generosity. That was my first mistake."
"Experience must be our only guide; reason may mislead us."
"Instagram is Twitter for people who can't read."