Social conservatives agree on traditional moral absolutes, which are essentially the same throughout the history of civilized human society. What has been considered virtuous and moral in sexual behavior have been amazingly consistent throughout history, and every monotheist religion as well as many that aren't such as Buddhism all share the same values. None have accepted same sex acts as anything other than unnatural and immoral.
Here's a statement by John Adams about virtue:
"We ought to consider what is the end of government before we determine which is the best form. Upon this point all speculative politicians will agree that the happiness of society is the end of government, as all divines and moral philosophers will agree that the happiness of the individual is the end of man. ... All sober inquirers after truth, ancient and modern, pagan and Christian, have declared that the happiness of man, as well as his dignity,
consists in virtue." --John Adams
Now that's conservatism in a nutshell. It's not just the RTKBA, or lower taxes, that is the foundation of conservatism. It's that social stability and progress has to be founded on public virtue. Many of the founders expressed that very explicitly.