So how old must a person be to sell his father's land? The first suggested age is sixteen. The second suggestion is twenty. Each rabbi suggesting these ages does so in accordance with other rabbis who have determined these ages in the past. A case is shared where a person sells his father's property and then dies. The family claims that the sale was invalid because he was a minor. They wish to have the rabbis check his body for signs of adulthood: two pubic hairs. Rabbi Akiva refuses because it is a disgrace and because the body might have changed after death. We are told that the young person was eighteen, but the family still hoped that his lack of body hair would disqualify him as an adult.
The rabbis wonder whether or not hairs should determine a person's status. For example, if this young man was eighteen - or even twenty - and had no public hairs, is he automatically thought of as a minor? Or is he classified as a eunuch, which is a man who does not develop secondary sex characteristics?* The rabbis ask whether someone without pubic hair might not be a eunuch. Might he be a minor? And what is a minor, anyway? Some rabbis believe that a minor is anyone under twenty. Others believe that a minor is under the age of half one's expected life of 70 years, thus anyone under 35 years old. We are reminded that men who approach rabbis when they are older and without hair might be told to gain or lose weight depending on their girth. Either might cause hair to grow.
What if the person had not yet turned 18 or 20? A number of cases are shared regarding this type of question. For example, what should we think of a young man who sold his father's property followed by and invalidation of his sale? This is not a good example, we are told, because he frivolously freed his father's slaves.** And what should be done if a girl of 14 understands business and sells her father's property? Does the sale stand? What if someone behaves as if his is a minor but inadvertently demonstrates his maturity? Does his sale stand?
Finally, we are privy to the rabbis' conversation about when young people are permitted to buy and sell on behalf of their families. Either at 18 or 20, the rabbis wonder whether they are permitted to speak for movable property/debts or whether they have access to decision-making regarding land as well.
* Masechet Yevamot 80 lists the characteristics specific to a eunuch
** From today's perspective, of course we wonder whether or not this young man was being frivolous at all by freeing his father's slaves. Perhaps he saw their suffering and reasonably wished for their freedom over the benefit of their monetary worth.