I believe this study has merit. I was born to a Jewish father and Protestant mother and was raised culturally jewish (we had dinner for high holidays, I was not bar mitzvahed). After going on Birthright, I felt a strong connection to the Jewish State of Israel. I decided that I will only marry a jewish girl because I want my kids to be raised and considered jewish.
U.S. confirms ISIS computer expert killed in air strike (Reuters)
from the article: Birthright alumni found less likely to marry non-Jews