Here is a version of seeds reverting to wild but I was told on here that doesn't happen. So maybe this crossed with some kind of root stock like swingle.
This tree grew from a seed. Someone ate an orange and spit the seeds out 20 years ago. The tree is healthy while others in the area fade from greening or similar viruses. Tree and leaf looks like an orange. Oranges are full of seeds. Like 100 seeds inside which is the biggest negative. Orange looks normal on the outside. Tastes sweet, good flavor. Very slight trifoliate off flavor. But to put in perspective people pick these and eat them. They are less good than normal oranges but good. Tree is not thorny. Tall shade tree like which is how citrus grows from seed where they are shorter and bushier from cuttings.
I snagged some seeds off an unripe fruit today. Since everyone picks them they are hard to.get.