Unequal Bequests

From Light and McGarry (2004):

Parents often appear to "play favorites" when distributing financial resources among their adult children. Recent studies indicate that in any given year, approximately 75 percent of parents who make inter vivos transfers to their children give unequal amounts. Even when making bequests -- where equal division is the norm -- as many as 20 percent of parents treat their children unequal.

They uncover lots of interesting patterns in the data.  For example:

The probability that a mother intends unequal bequests is significantly higher if she is in poor health ..., if she has nonbiological children, and if her children's predicted incomes are especially different from each other.