How to aggregate features to a group level as a feature in machine learning model?
Ages
I guess adding up the ages won't makes sense, since the number 30 means that there is one person of 20 years and one of 10, or a bunch of 5 years old?
What you could do is have number_of_adults_in_household and number_of_children_in_household. This way you still aggregate the ages but keep more information.
Education
Education might be a more difficult feature to aggregate. My educated suggestion would be to have highest_education_degree_in_household.