Sami converted. Whoopie is not jewish. Kravitz is part jewish on his father's side. Bonet is jewish on her mother's side.
Jones is jewish on her mother's side.
So are they Jews or not? Is someone who practices Judaism a Jew? Is someone who has Jewish blood who practices Christianity or Atheism still a Jew?
To orthodox, they don't welcome converts. Mostly it depends on if you practice your faith or do you identify with the faith of your parents. You can be a jew by birth but not actually practice the faith. Some only observe holidays and high holy days.
Like any religion it depends on the individual and what feel inside.
You do not need to be a member of a synagogue to identify as a jew. You don't even have to be jewish to say your own prayer at the wall or leave a note. You don't have to be jewish to observe the holidays.
You can enter any house of worship no matter your professed faith and feel a connection to a higher power, something greater than yourself.
You decide your identity no matter who your DNA is from or what your were taught growing up.
Too make an aliyah or actually become an Israel as a jew is more complex. It is not just religious but legal qualifications involved.