I don't think you are strange (or, if you are, so am I!)

Other people's kids are normally a pain in the arse, mainly because we aren't allowed to tell the doting parents how obnoxious their little darling really is. At least when the brat is your own, you can be honest but, of course, your own kid is always going to be so much better! And it is instinctive when you are delivered a little bundle of joy...

As for no feelings for your estranged dad, why would you be surprised? He's not part of your life - and whether that is his choice or yours, he just isn't important to you.

Brothers/sisters/extended family? You choose your friends, not your family, so you may just not get along, but I would encourage you to try. I never kept in touch with my sis or my cousins for years, and even now we can go for months at a time but we all seem to get on well when we do get together - shit, we even went on holiday for a week in 2008!