Some people think that they are nothing like their siblings, or may notice many differences in looks and behaviors. This is partly because siblings don’t share all the same genes. So, if your brother or sister tested negative on a carrier screening test, it does not guarantee that you will also test negative.

It is possible that you inherited a genetic change that your sibling did not, and the best way to find out is through testing yourself.

Also, males and females are sometimes tested for slightly different conditions. It is possible that there is additional testing available to you that was not available to your sibling.