You're saying like it completely invalidates the results. It might, but you'll have to read the study and show some calculations; or it might not, I personally

You're saying like it completely invalidates the results. It might, but you'll have to read the study and show some calculations; or it might not, I personally don't know, I'm not a statistician. For what it's worth, the study addresses the sample size: "We aimed to recruit 22 pairs of identical twins 18 years or older, a sample size determined by resource availability rather than a formal power calculation. "