Almost all commercially sold citrus is grafted. Citrus is generally not true to seed, so a known good fruit branch will usually be grafted onto a seed grown citrus species that is specifically grown to be grafted onto. This not only ensures that the fruit is produced as advertised, but also helps the plant reach fruit production more quickly.
Disclaimer: I’m just some guy with a few fruit trees, definitely not an expert.
Your house is also probably a lot bigger than what’s pictured.