As is known, Mendeleyev was born in 1834 at Tobolsk, in the far west of Siberia, into a well-educated, reasonably prosperous and very large family, but how large? Some sources say there were fourteen children, some say seventeen.
Three of the seventeen children died before they were baptized, so they don't even have names. For this reason, the church records list only fourteen children.
In total, eight of his siblings died in infancy.
Maria died when she was 15, Appolinaria died at the age of 26, and Elizaveta at the age of 29. Only four lived until 70.