The obvious answer is that we have different fathers, but this is definitely not the case since we all look quite a bit like my/our dad. I am the youngest, yet I always did extremely well in school, while both of my siblings were pretty average, really. The gap widened post high school as neither of them finished college, while I have gone on to earn a PhD in a STEM field. Both of my siblings literally struggle to hold down a job of any kind... My brother works in manual labor and my sister has been fired from multiple minimum wage jobs (bussing tables, answering phones, etc). Besides that, both of their lives are kind of disasters. They've both wrecked more cars than I will probably ever own, neither can maintain relationships, both are in terrible physical condition and drink a lot... I just don't get it. The contrast is so great it reminds me of the movie Twins where Arnold Schwarzenegger and Danny Devito are brothers.
Anybody have any idea how common this is or even know of any similar cases? I do not personally know a single other individual comparable to me who can relate.