Here's a thought. I think everyone is capable of pretending (aka: faking) that they like someone they don't particularly like. I do it all the time. If we all went around telling each other exactly how we feel about each other, I'd venture a guess that none of us would have any friends or relatives that we speak to on a regular basis. I know I wouldn't.
And so, if you're a relative of mine and you decide to call this house and I pick up the phone, how about you pretend that you like me, or at the very least, that you recognize my voice since I've been married to your son for over 20 years. It's not that difficult to fake kindness once you get the hang of it and I know you have it in you because you're nice to everyone else in this house but me.
If you need tips on how to be a hypocritical phoney who knows how to fake kindness, take careful note of how I speak with you every time I speak with you.