Twins Two Years Apart

When I started having children I assumed we would like everyone else.  We would sit on the church pew with our children that looked like twins two years apart.  Well things never quite happen like I expect, and my children did not come two years apart, due various reasons. My first child looked quite a bit like both my husband and I, so I assumed all our children would be like that. My husband was born with a full head of hair, I was born with a full head of hair, and my first child was born with a full head of hair.  A little shy of three years later my second child was born.  She didn't look anything like the rest.  She was bald, she ended up being blonde, she had bright blue eyes, she didn't have my husband's eyes/son's eyes. None of us are blonde and blue eyed? Truly where did she come from? (I ignored the fact that the majority of our nieces and nephews on both sides of the family are blonde and blue eyed.  Then she grew into green eyes, like mine.)  Plus she cried incessantly for two years.  Why didn't I have my twins two years apart, like all those other families?
Well four years later, I didn't get my twins two years apart, but almost four years later, I did get my twins, four years apart.  Now the eldest child is the one that doesn't look anything like the rest.  Ok, to be fair I think my third is going to be the missing link between the first two. But it is fun, now to have my baby that is the spitting image of the older sibling, still I'm wondering how two people born with hair, are 2/3 for bald babies?