Is it common to kiss your family on the lips?

I went to a cookout with my good friend and her family yesterday and I was a little shocked. As we were leaving she went to her mom, dad, grandparents, brother, sister, and two aunts and kissed them all goodbye on their lips.

I'm not saying "ew that is gross and wrong". I just had no idea that people actually do that. I grew up as a kid kissing my close relatives on the lips but as we all got older we just hug and do cheek kisses.

Is this kinda strange for anyone else? Or Do you kiss your family on the mouth?