[lidHanteyk]

So don't mix those two things, then; keep them distinct. Work to preserve the acyclic property, rather than trying to toss new concepts in.

[rhn_mk1]

This works only until the concepts are the reason the problem is being tackled. A family tree based only on genetic relationships is interesting to few people outside geneticists and doctors. Most people are interested in familial ties as they are culturally defined.