I hate when people try to talk about families T___T

I just happened now.
But this is how it generally goes

So how old are you parents?
Parent.
Parents.
Mom is xx.
And your Dad?
I... don't...have....a dad.
 

And their face is instantly one of regret. If I had to choose a word. As in, they feel guilty for having asked.

What sometimes makes it worse is that I then start laughing. Because i actually find it funny. They way they react. I wonder what exactly they imagine. 
 

So I just go I don't know where he is
So you don't know him?
No....
Are your siblings from the same..
Yes
Oh... so he just left after you were born.

Insert the biggest silence you can ever imagine. And then it just gets weird.  :<

He just literally said that he felt guilty and nosy for asking. 

Urgh.

My head hurts.