Our Lemon Tree War

Ten years ago, My wife and I went on a trip to Florida with some friends. It was during the strawberry season, so we went to a nursery to buy some strawberry plants. I bought this tiny lemon tree in a qt. milk container. It had a three inch sprout and I wanted to see if it would grow in PA.
The plant turned out to be a fantastic producer (after about four years of no fruit or blossom). I get a dozen large lemons each year. They are ready to pick around Christmas.
My son and his wife and children went to Italy about four years ago and he raved about the huge lemons that they have. Customs would not allow any of their precious lemon trees to leave the country, so, he couldn't take a lemon home.
Somehow, and I don't know how, .... He had these special lemon seeds in pots on his patio. His trees are almost eight feet tall now,.... but ......no lemons. He keeps telling my that when they reproduce, they will knock the socks off of my puny lemons. ... so, ... the war is on.
I did manage to get a tiny seedling from him (one of his runt plants of course). I would like to cross breed the two trees.
You can see by the photos that my lemon tree will have a bumper crop this year. ..... his trees, .... no fruit yet.
The last photo (sorry about the sideways pic), shows my little runt lemon is catching up to his monster (non-producing) trees.