Rand emphasized self-sustaining as the key attribute of living things. This was in a long tradition of biological thought.
Lately there has been more emphasis on self-reproducing as the key attribute. This makes it easier to count viruses and genes as alive.
So who is supposed to be selfish here, the Person or the Gene?
It's the problem of the chicken and the egg.
It keeps on going - boy it has great legs.
I've self-sustained and also reproduced.
I guess that gives both sides a little boost.
Perhaps it's two sides of a single coin.
At least it's clear how often they are joined.