I’ve been contacted by a woman (let’s call her Kate) from my mom’s home country, who has done pretty extensive DNA testing to build out her family tree and has had multiple of her family members DNA tested. Before she emailed me out of the blue, I’ve never heard of this woman before as she and her family were completely unknown to myself and my family.

Her results have shown that my mom’s father (my only living grandfather) isn’t my mom’s biological father and that it’s Kate’s brother is the actual biological father.

There are 2 possibilities that explain this - A. My grandfather knew my grandma was pregnant with another man’s baby when they got into a relationship and still married her.

B. My grandma cheated on my grandfather.

My grandparents got married 5 months before my mom was born so these are the 2 possibilities.

Am I wrong for not telling my mom what this woman has informed me of?

If either A or B is true and both unknown to my mom, I feel as if it’ll cause a lot of stress. My mom is also almost elderly so I don’t want to cause her any stress.