Depends on what you mean by this. If you mean involving them in it, then yes, probably (qualified because I know of no actual research on the matter; nor do I know of any way such research could be conducted so we will probably have to settle with 'yes, probably' as the closest answer to accurate).

If you mean allowing them to be aware of it as something that adults do, and occasionally seeing adults engaged in sexual activity, then no. The behavior of shielding children from both even having knowledge of sex, and witnessing it performed by adults, is relatively new, largely taking hold after the Reformation based on my relatively surface-level dives into the subject in the past (I have learned that going deep into this is difficult, the scholarly texts are long and difficult to read for laymen). In medieval times and before, children were aware of adults having sex; they often could not be kept unaware because there was no place for the adults to gain privacy. The modern view of the past is bizarrely anachronistic in that we project prudishness and avoidance of sexuality to a time period centuries before it actually became that way.

Thus, it becomes clear that the avoidance of children being aware of sex existing and happening is a very specific cultural phenomenon that does not paint an accurate picture of actual harm to children, and is based primarily in christian moralizing.