Characters can take after (or rebel against) their parents, traits like alcoholism are self-perpetuating, inbreeding tends to strengthen when inherited, naivete and paranoia are mutually exclusive but both detrimental, etc.
To add some confusion, the term hybrid inbred applies to hybrids that are made from selected inbred lines that have certain desired characteristics (see inbreeding).
The remaining populations are often geographically isolated from one another, which can lead to inbreeding, and consequently, reduced genetic diversity.