I have no respect for my friend's sister for being a young mother
why don't you have respect for your friend's sister?
She got pregnant four years ago when she was just 16 years old and gave birth to a daughter.
Sure, it isn't great getting pregnant and being a mom before you finish high school, but she's isn't any less of a person because of that.
I'm just saying she's going to be a bad mother with no maturity and will be a bad influence on their child.
Assuming she will be a bad mom is just bias from you. You have no basis for judging her her so harshly in hat way. Instead of judging her, why not offer her help if she needs it or asks for it.