"I can't understand why men would ever want to go their own way!"

This also implies that guys who does not suspect and don't do the test are not included. Since you can't measure how aware parents are about this things nor how much is the sample biased, the proper conclusion is to asume the sample expels a proper aproximation, with a possible error based on how many total tests were done.

What i mean mean is, yes, it could be less than 10%, and is the logical thing to asume considering there's a potential bias.

But there's also a chance it's even more than 35%. And this is scary af. For example, if the state in which the study was done, there's a collective male paranoia about this topic, it would contaminate the sample and serve as a counterbias since a lot of biological parents would ask for a test without further motivation.