That does happen a lot, when a male "accidentally" has sexual intercourse with a female.
Unprotected sex somehow leads to pregnancy, and here I am thinking we beat nature by finding a way to screw without consequences.
Badly, very badly. At least that's what I'd think if I had a half brother because my dad was irresponsible, and him not being with either mom.
There are many factors determining how your children will view you. If you want good results, do this:
1) Work hard to be financially successful.
2) Be present in their lives.
3) Be a good example for them to follow.
4) Educate yourself on birth control.
If you can't do these things, you don't deserve anyone's approval. If you do, you can justifiably feel good about yourself.
That's pretty low down, in my opinion, they probably won't have anything to do with you. Sounds like you're not very responsible.