I need advice on a personal Matter...?

I am a guy and I have a scar on the shaft of my penis. I have had the scar for as long as I can remember, So I have to recollection of how I got it. I want to ask my mom, but how would I go about asking her something like that while I am 15 years old? Anyone got some advice for me? It would be very helpful because I really want to know how it got there but it seems like an awkword question to ask a parent...