Rana has zero grasp of statistics
She managed to glean from a quick glance at a webpage that Steve has 50% chance of inheriting the gene. Michelle asked what that would mean for the baby and was there anything that could be done, and Rana pretty much said No.
What she should have said is "Well, the baby then has 50% chance of inheriting the gene, giving an overall chance of your baby having it of 25%". That would've been more reassuring surely.
I'd never want Rana advising me on my health, what a pessimist!
I am ANYTHING but a pugnacious upstart