Albert Einstein's consanguineous marriage

In previous blog posts, I have mentioned several well-known people who were involved in consanguineous marriages, which is defined as the union of two people who are related as closer than second cousins. In the first post (Charles Darwin's family pedigree network) I discussed in detail Charles Darwin (who married his first cousin); and in a later post (Toulouse-Lautrec: family trees and networks) I discussed the artist Henri Toulouse-Lautrec, who was the offspring of a marriage between first cousins. Now, it is the turn of Albert Einstein (1879-1955).

Einstein's first marriage (in 1903) was to a former fellow physics student, Mileva Marić (1875-1948). They had three children: Lieserl (1902-?), who was born the year before they married, Hans Albert (1904-1973) and Eduard (1910-1965). Einstein seems to have been far from the ideal husband or father, as detailed in the book by Roger Highfield & Paul Carter (The Private Lives of Albert Einstein, St. Martin's Griffin, 1994). Some brief information is given below.

When the marriage ended, Einstein married (in 1919) Elsa Löwenthal (née Einstein) (1876-1936), who brought with her two daughters from her own first marriage: Ilse (1897-1934) and Margot (1899-1986). As shown in the family pedigree below, Albert and Elsa were first cousins through their mothers (traced in red) and second cousins through their fathers (traced in blue). [NB. This is only part of the family tree.]

The main issue here is that this pedigree is a reticulating hybridization network, rather than a diverging tree, which clearly shows the problems with consanguineous marriages. The genetic diversity of any individual born from such a marriage has a much higher risk of expressing recessive genes in their phenotype, many of which cause serious health problems. For example, several of Darwin's children died young, and several others were apparently infertile. As well, Toulouse-Lautrec is well-known for his short stature and genetic deformities, and his brother died young, and several of his cousins (also the offspring of a consanguineous marriage) had the same genetic problem's as himself. Consanguineous marriages are not encouraged, if children are an intended outcome (see Bennett et al. 2002. Genetic counseling and screening of consanguineous couples and their offspring: recommendations of the National Society of Genetic Counselors. Journal of Genetic Counseling 11: 97-119).

Elsa and Albert are not known to have had any children (but see the note below), and it has been assumed that they had a relatively platonic relationship. So, this particular story does not have the same sad ending as those of Darwin and Toulouse-Lautrec. It would be interesting to know whether Albert and Elsa's childless state was a deliberate decision (in light of the possible genetic problems for any child), a consequence of age (they were in their 40s when they married, which makes pregnancy risky), or a result of (unreported) miscarriages.

The following note about Einstein as a husband is from The other side of Albert Einstein:

Einstein was far from the ideal husband. A year before they married, Maric gave birth to a daughter, Lieserl, while Einstein was away. The child's fate is unknown – she is presumed to have been given up for adoption, perhaps under pressure from Einstein, who is thought to have never seen his first born. After the marriage, Mileva bore two sons but the family was not to stay together. Einstein began an affair with his cousin Elsa Löwenthal while on a trip to Berlin in 1912, leaving Mileva and his family two years later. Einstein and Mileva finally divorced in 1919 ... Einstein married Elsa soon after the divorce [he had been living with Elsa for nearly five years], but a few years later began an affair with Betty Neumann, the niece of a friend. By one account, Elsa allowed Einstein to carry on with this affair to prevent him sneaking around. That relationship ended in 1924, but Einstein continued to have liaisons with other women until well after Elsa's death in 1936.

For information about a possible child of Albert and Elsa in 1932, see Einstein's son? It's a question of relativity.

Composers and consanguinity

There are many other people whose names are well-known and who were involved in a consanguineous marriage. Notably, there have been several composers of classical music:

• Johann Sebastian Bach married his second cousin, Maria Barbara Bach. The pair had seven children together, but only four survived to adulthood.
• Edvard Grieg married his first cousin, Nina Hagerup. Their only child, a daughter, died at the age of one. Around the same time Nina also had a miscarriage.
• Sergei Rachmaninoff married his first cousin, Natalya Satina. They had two daughters who survived to adulthood.
• Igor Stravinsky married his first cousin, Yekaterina Nossenko. They had four children surviving to adulthood – two sons and two daughters.

Note that this type of marriage was very unusual for Rachmaninoff and Stravinsky, because the Russian Orthodox Church explicitly forbids marriage between first cousins (both couples needed to get permission from the Czar), and so the families involved also opposed their marriages. Apparently, the relevant families also opposed Grieg's marriage. Indeed, it is reported that Edvard and Nina were surprised and disappointed to find out that they were not able to have children together.