My (F, 28) weight has been stuck at 67 kgs for years

I'm (F, 28, 167 cm) and my weight has been stuck at 67 kgs for years. I've weighed pretty much consistently the same since I was 21 years old with no changes.

Over the years I've yo-yo'ed slightly, gaining a few kgs and losing a few kgs, never more than 1-3 at a time, but I've always ended up back at around 67 kgs.

I would say I am pretty healthy. I don't consistently count calories (I used to for years to no avail). I don't binge, I don't snack, I eat healthy and in moderation -- focusing on high protein/low carb, I avoid sugar. I exercise pretty consistently and when I don't I make sure to eat in a deficit. At the gym I combine cardio and weight lifting, sometimes I do pilates or yoga instead.

I don't understand why my weight never changes. One thing I have noticed is that the women in my family tend to be quite overweight overall. Everyone on my moms side of the family is very overweight/obese and they all seem to have a hard time losing weight. Could genetics be a factor?

Help! This has been plaguing me for YEARS -- what can I do?