Your ancestors look serious in their photos because they had a lot to survive. Smile in yours; they earned you that.

The seriousness in those photographs was circumstance rather than personality. Long exposures, hard years, very little margin when anything went wrong, and most of what they did was aimed at making a life further down the line easier than theirs was. Whatever ease you have is partly their output. Enjoying it is not disrespect, it is the entire point of the exercise.

Take a picture this week with people in it and do not arrange your face. Laughing, mid sentence, badly lit, it does not matter. Then print one, because a photo living only on a phone is not in the family record yet.