A Yale University group last week cancelled its plans for a debate on genetics between William B. Shockley, the controversial Stanford professor, and Roy Innis, national director of the Congress on Racial Equality.

In a 200-190 vote Friday, the full membership of the Yale Political Union decided to call off the debate, three weeks after the group's executive committee had invited Shockley and Innis to speak.

The executive committee decided last week to break with its usual procedure of inviting speakers without consulting the group's full membership because of widespread protests at Yale to the debate.

However, the debate still may go on. A conservative Yale alumni group, Lux et Veritas, announced after the political union vote that it will invite Shockley and possibly Innis to speak at Yale.

Shockley said yesterday that Lux et Veritas has not yet approached him about rescheduling the debate.

Praise From Brewster

After Lux et Veritas announced its plans Saturday, the Yale Corporation and Yale President Kingman Brewster Jr. issued statements praising the political union's action and criticizing Lux et Veritas for trying to invite Shockley to speak.

Shockley, a professor of electrical engineering and Nobel laureate in physics, and Innis were scheduled to debate at the Harvard Law School Forum last October, but the Law Forum cancelled the debate under pressure from black law students and professors.

Shockley said yesterday that the Yale cancellation proves "that universities do not encourage belief in the power of inquiry to find truth."

Blood and Brains

Shockley believes that blacks are genetically less intelligent than whites, and that intelligence in blacks is directly proportional to their percentage of "Caucasian blood."

He has also proposed as what he calls a "thinking exercise" the idea of cash government bonuses for people with genetic deficiencies, including low intelligence, who voluntarily undergo sterilization.

Innis and Shockley have debated once, last December, on NBC's Tomorrow television show. The pair was scheduled to debate at Princeton University in December, but Innis announced three hours before the debate that he would not participate because the Princeton administration would not allow non-students and non-university press to attend.

Innis has initiated all the planned debates because he says he can disprove Shockley's theories in a debate.

Shockley debated Alvin F. Poussaint, assistant dean of students at the Medical School, on the David Susskind television show in December.

Shockley yesterday challenged the presidents of Yale, Princeton and Dartmouth, all of whom he said have "derogated" his views, to debate him. THE SHOCKLEY-INNIS SCORECARD Debates Scheduled  Shockley  Innis  Notes Harvard, October 1973  CANCELLED Tomorrow Show, December 1973  *  *   Princeton, December 1973  *  Cancelled  Debated Montagu David Susskind, December 1973  *  Not Invited  Debated Poussaint Yale, March 1974  CANCELLED