Relational distance off-by-one

[rhagenson]

I realized just now (after not seeing any parent-offspring relationships in the pedigree) that I have an off-by-one error. I use a distance of 1 to represent a parent-offspring relationship (the child is 1 link away from parent, and vice versa). However, when I add "unknowns" I add the same number as reported distance. Therefore I am over-creating unknown individuals by 1 each time.