Number_6 said:
You're mistaken. The original draft to "Journey to Babel" included an uncomfortable scene between Kirk and Spock after he found out that Sarek was Spock's father.
In the original, it turns out that the young Kirk was sent to Vulcan for therapy after his experiences on Tarsus IV. He was so distraught by the carnage under Kodos that he had become almost catatonic.
The services of a Vulcan expert in melding with a human were required, and that obviously led to Sarek. Their melds were so deep and so satisfying that the relationship was taken to a physical level, as it had been with Amanda.
It's really too bad that Stanley Robertson at NBC wasn't more open-minded (which you might have expected from an African-American in the 60s). Still, even if it had made it past him, it would never have made it past the network execs.