In the end, and I follow the issue of privacy quite closely, put it on line especially ancestry or any commercial for profit organization, there will be no privacy. And that includes myheritage.
privacy in these matters no longer exists in general terms.
until nations and governments and voters pass strict laws to protect it, you are dreaming to think otherwise.
if you don't want it shared, don't share it.
it will be shared under the current regime regarding privacy.