In order to be born, you needed:

2 parents
4 grandparents
8 great-grandparents
16 second great-grandparents
32 third great-grandparents
64 fourth great-grandparents
128 fifth great-grandparents
256 sixth great-grandparents
512 seventh great-grandparents
1,024 eighth great-grandparents
2,048 ninth great-grandparents

For you to be born today from 12 previous generations, you needed a total of 4.094 ancestors over the last 400 years.