Is it good to have null values with normalized data?

I have tables like customers, resources, affiliates, members,... which all have a profile_id as foreign key. The common data(like: name, email,..) is stored on profiles. Now, there are some data (education, employment, mfs_account,..) which are related to only some table(resources and members, not customers and affiliates). Should I store those data to profiles(which will have a lot of null values, approximately 4:1) or individual tables(which I think is against database normalization technique)?