Both belong to the same family, making them biological "siblings." You can actually graft a tomato stem onto a potato root to create a "Pomato" plant that grows both at once!

Nature often hides its family secrets in plain sight. While one gives us juicy red fruits for salads and the other provides starchy tubers for fries, the tomato and the potato are incredibly close relatives.
Both plants belong to the Solanaceae family, also known as the nightshades. This family also includes peppers, eggplants, and tobacco. Because their DNA is so similar, their tissues are compatible enough to fuse together through a process called grafting.
The "Pomato" (a portmanteau of Potato and Tomato) is not a genetically modified monster or a seed-grown hybrid. It is created by physically joining the top of a tomato plant to the root system of a potato plant.
While it sounds like a science experiment, the Pomato is a practical solution for urban gardening. It allows a gardener to harvest two different crops from the exact same square foot of soil. It's the ultimate space-saving hack for small gardens or balconies.
Tomatoes and potatoes are so biologically identical in their "plumbing" that they can be combined into a single living factory. It is a perfect example of how human ingenuity can leverage the natural family ties of the plant world.