You have a good point, but I would like to think that forgiveness and unconditional love makes one a better person.
If someone has never given it, they will never receive it. It is possible for a relative to kill any love, if they try hard enough.
Take an example where a parent makes contact an exercise in misery every time a child reaches out to them, and they persist in doing it for decades. Even a saint has limits. After a while, they become strangers, by the choice of one party.