I don't "spank" my children. I also don't hit any other members of the family. I expect that none of them will hit me. To my mind, hitting kids is both ineffective and inhumane. Apparently my views were shared by the Roman orator, Quintilian (35-95 A.D.), who wrote:

"I disapprove of flogging, although it is the regular custom... because in the first place it is a disgraceful form of punishment and fit only for slaves, and is in any case an insult, as you will realise if you imagine its infliction at a later age. Secondly if a boy is so insensible to instruction that reproof is useless, he will, like the worst type of slave, merely become hardened to blows... And though you may compel a child with blows, what are you to do with him when he is a young man no longer amenable to such threats and confronted with tasks of far greater difficulty? Moreover when children are beaten, pain or fear frequently have results of which it is not pleasant to speak and which are likely subsequently to be a source of shame, a shame which unnerves and depresses the mind and leads the child to shun and loathe the light. Further if inadequate care is taken in the choices of respectable governors and instructors, I blush to mention the shameful abuse which scoundrels sometimes make of their right to administer corporal punishment or the opportunity not infrequently offered to others by the fear thus caused in the victims. I will not linger on this subject; it is more than enough if I have made my meaning clear. I will content myself with saying that children are helpless and easily victimised, and that therefore no one should be given unlimited power over them."

From Quintilian's Institutes of Oratory (Institutio Oratoria) written in the 1st Century A.D. Translation by H.E. Butler, published by the Harvard University Press in 1936, in the Loeb Classical Library.