My son was born (two years earlier) on what ended up being my nephew’s due date, and that nephew was born on my son’s original due date (two years later.) My daughter and my other nephew were born a week apart (with another two year difference.) My niece and my youngest were born on the same date years apart. The 2 nephews and niece are all my sister’s children, and we each only have three kids. My parents, husband, self, and kids’ birth years, and our anniversary all fall on even years.