18 years old, history MPB in family

[budm2000]

Just noticed a bit of recession across the temples, or more accurately my left temple. I've looked back at photos of myself as a younger teenager, and the hairline on the left (from the viewer perspective) seems to have remained more or less the same. Which really begs the question, if I am maturing, why is it on one side of my head? Or is there something else at play here? The hair around the right temple is noticeable thinner than that on the left. Would love to hear some thoughts.