There is no way to gift gold directly, as Prof Greyrose said, however you can trade treasure cards which can be sold for gold. You can also fight bosses for drops that can be sold for gold, and if your higher level character helps that can add up quickly.
You said we can sell treasure cards. Who buys the cards?
We have looked and cannot find how to sell them.
Most Treasure cards can be sold at the Bazaar. It's pretty common practice to store excess gold in the form of expensive TCs, and to trade them to lower levels who need gold.
You said we can sell treasure cards. Who buys the cards?
We have looked and cannot find how to sell them.
Ahh I think you misunderstood. He meant you could "trade" them to your son (have your son put zero treasure cards in when he clicks ready) so you can transfer treasure cards over for your son to sell at the bazaar