potatoes from seed

i transplanted this tangle of potato vines ( top photo ) into peat pots as seedlings 114 or 115 days ago depending and while the basement seed potato project is winding down ( only two plants left ) these critters seem determined to carry on indefinitely...and they are acting more like vines than any potato plant propagated from a tuber i have ever seen...they have grown along the top of the soil in all sorts of twists and turns ( second photo ) and where nodes in the stems are touching the soil they are putting down new roots ( third, fourth, and fifth photos )...i haven't seen any plant grown d=from a spud do that...i stuck my finger in the third photo because the contrast between the root and the soil wasn't that great ( see fifth photo ) and in the fourth photo the root is that tiny filament just at the end of my finger...the next step is to germinate more seed and grow the plants outdoors to see if they were behaving this way because of environment or if this is they way they are hardwired genetically...if and when they die back i will be checking for tubers...they have been putting out stolons as well as roots and those i have been covering with more soil...still, some of those have popped up and leafed out...so no telling quite what's going on ( in my experience anyway ) they are perennials and it could be they are confused by the artificial environment and not getting a cue that the season has ended...at least one grow light will continue to burn in the basement...apparently long after the rest have finished their work.