Una had augments added after birth. La'na only is decedent of Khan. She herself has no added augments (beyond what she was born with genetically). That's my guess?
Edit: I guess that's kind of what you said in the post description I didn't read close enough
Not necessarily - real gene therapies that are in use now are carefully designed so that modifications are not inherited. For example, Casgevy which targets blood stem cells to treat sickle cell anemia. Because the treatment is limited to specific types of cells modifications don't get into the germ line.
Depends if they altered her eggs too. It's a different story with dudes, who produce gametes for all their lives, as opposed to women, who are born with all the gametes they will have.