A Career in Singing.?

I am interested in a career in singing,and I'm worried my mom is going
to tell that I can't sing,btw she thinks Justin Bieber can sing
well,(I know that doesn't have anything to do with me I'm just
implying that maybe she has bad taste in music) My question is how do
I know if I can really sing or not,I don't want to try to pursue a
career in singing to find that other people don't think I can sing and
embarrass myself and I am too afraid to ask my mother for her opinion.