Conversation so far:
What support did Joseph McCarthy provide for Roman Catholics?
As his fame as a leading anti-Communist grew, he became popular in Catholic communities across the country, with strong support from many leading Catholics, diocesan newspapers, and Catholic journals
How was Joseph McCarthy involved with the Kennedys?
McCarthy became a close friend of Joseph P. Kennedy Sr., himself a fervent anti-Communist, and was a frequent guest at the Kennedy compound in Hyannis Port, Massachusetts.
What did Joseph McCarthy's involvement with the Kennedys entail?
He dated two of Kennedy's daughters, Patricia and Eunice. It has been stated that McCarthy was godfather to Robert F. Kennedy's first child, Kathleen Kennedy.

Question: How did they influenced each other?
Self-contained rewrite: How did Joseph McCarthy and the Kennedys influence each other?