For a young person born around the year 2000, there may be 7 or 8 generations on their family tree. Naturally, the number doubles with each generation. If one manages to trace seven generations of ancestors, the data of 255 individuals—including the person themselves—will appear on the family tree.
If all key data (birth, marriage, death) are successfully gathered, the resulting chart is truly impressive.
However, there are significant exceptions where, while all available data for every ancestor is included, the total number of ancestors falls short of the theoretical 254. There are two such scenarios that occur in almost every family.
The number of ancestors decreases in cases of “ancestor loss” (pedigree collapse). This does not refer to losing ancestors due to negligence! It simply means that certain ancestors may appear on two or more branches of the family tree. It is particularly common in small settlements or among aristocratic families for second or third cousins—or even more distant relatives—to marry; in such instances, the couple shares the same grandfather, great-grandfather, or great-great-grandfather, and so on.
European history offers striking examples of ancestor loss. In the seventh generation of ancestry, there ought to be 254 individuals. Yet, the Hungarian Queen Maria Theresa (1717–1780) had only 113, the heir apparent Franz Ferdinand (1863–1914) had 101, and… For King Alfonso (1857–1885) of Spain, 48 (!) individuals appear in the eighth generation of his ancestry.
What is the noticeable sign of ancestral loss when the degree is this high? Genetic inbreeding develops in such families. In fortunate cases, this does not result in obvious physical or mental impairment, yet some issue is almost always detectable.
However, we should not assume that ancestral loss is rare or occurs only in extreme cases. It is statistically demonstrable that every Hungarian counts Prince Árpád as an ancestor through multiple lineages, while families of long-standing nobility almost certainly descend from one or more European monarchs.
Another cause of ancestral loss—though this merely renders it impossible to identify the specific ancestor—is illegitimate birth. Illegitimacy occurred (and still does, though we no longer use that term) when an unmarried woman gave birth. In such instances, the notation “illegitimate” was entered next to the baptized child’s name in church registers; consequently, the paternal line of the family tree was lost. There were cases where the father later married the mother and the child was legitimized, making it possible to research the paternal line if records of this legitimization exist. It frequently happened that another man married the mother of an illegitimate child and gave the child his surname, but this does not remedy the loss of the biological paternal ancestry. “Ancestor loss” must also be taken into account when a child has been adopted, as the adoptive parents are not biological ancestors.
When ancestor loss occurs due to the presence of shared ancestors, it creates a visually striking pattern in the family tree diagram. The diagram illustrating the ancestor loss of Dániel Berzsenyi’s children serves as an example of this.
It requires immense luck for all 254 individuals to be present in the seventh generation of a person’s ancestry. As one traces the lineage further back in time, available parish registers and documents become increasingly difficult to access and contain less usable data; consequently, one or more pieces of information regarding a name may be missing.
