I look like my father and and have almost no physical appearance qualities in common with my mother or her family. Oddly enough, I'm pretty tall at 6' 2" and stand head and shoulders above people on both sides of my family.
I have a half sister (same mother, different father) who looks nothing like me and was born 21 years later than me. It always a funny reaction when I (40 years old, tall, and pale) introduce her (19, short, dark) as my sister. People usually look back and forth between us then their forehead wrinkles up in confusion, lol.