It's suggested that the use of gene selection is widespread though so can't be that expensive "like most other parents of the day".
She belongs to the elite already so you'd imagine has more money than Ethan's parents.
The only thing I could think of is that there is still some chance left in the gene selection in that
i. you can only select genes that are there* and
ii. there are still some unpredictable factors (hence her heart problem).
If so tho it would not just be the genes that matter per-se but also how likely those particular genes are to be transferred to children (how likely they are to be copied over).
*remember when breh doc said it is still you, just the best of you.
also lamar (doc) at the end said my son is not quite what they promised.
also the flight boss admitted than even the gene kids have various levels.
Picking a good partner meant better odds
.