SCRIPTURE, THE POPES, BISHOPS, PASTORS, and authorized Catholic teachers have for centuries proclaimed as a significant part of Christian moral teaching that homosexual acts are intrinsically morally wrong. In recent years, however, some have challenged this teaching. For example, in a Quaestio disputata in this journal in 2006, Todd Salzman and Michael Lawler (hereafter, S/L) say that this teaching is incorrect. (1) They argue that what they refer to as merely "the magisterium's teaching," is based on the mistaken tenet that heterogenital complementarity is a sine qua non of a truly human sexual act. (2) Instead, they claim, a broader view of complementarity enables one to see that some homosexual acts can be objectively morally right inasmuch as such acts possess an "orientation complementarity," a complementarity that integrates a "personal complementarity" in a sexual act. S/L contend that homosexual partners can have a "personal complementarity," and that this can be "embodied, manifested, nurtured, and strengthened" in homosexual acts
Cross-sectional and longitudinal research both suggest that similarity (“birds of a feather flock together”) is a better predictor of relationship quality than complementarity (“opposites attract”). But, it is important to note that this conclusion is also a gross oversimplification. The degree of similarity observed depends on the particular individual-difference domain studied, with romantic partners showing strong similarity in age, political, and religious attitudes; moderate similarity in education, general intelligence, and values; and little or no similarity in personality characteristics (6,13).
[A]ccording to the “complementarity hypothesis” individuals feel most attracted to potential partners who complement them, an assumption that reflects the saying that “opposites attract” (e.g., Antill, 1983). Complementary individuals are assumed to be so attractive because they enhance the likelihood that one’s needs will be gratified (e.g., De Raad and Doddema-Winsemius, 1992). For example, young women who lack economic resources may feel attracted to older men who have acquired economic resources and therefore may be good providers (Eagly and Wood, 1999). In addition, from an evolutionary perspective, one might argue that seeking a complementary mate, rather than a similar one, may help prevent inbreeding.
People do prefer those who are similar in background, interests, and values. They want to talk about things that interest them and do things familiar to them. A person who can provide social support by having similar beliefs and values is a likely potential friend. Despite the folk wisdom that opposites attract, similarity is more powerful than complementarity. The exceptions are those with strong needs on either end of the dominance–submission continuum or the nurturance–succorance continuum (Argyle 1969, p. 213); when strong needs exist in these areas, complementarity is more powerful.