1. Vis for genealogy 2. Vis Nuclear families 3. Contextual Family Tree 4. Vis Consanguinity
The plots discussed in the previous pages raised the awareness of consanguinity in families. That led to the pursuit of visual representations for analyzing consanguinity.
The figure below shows the family trees of my wife and me enhancing our common ancestors, Constantino do Vale Pereira Cabral and his wife Maria Ribeiro Coelho, who are our great-great-grandparents.
The orange dots and the label indicate our kinship, and the green label our coefficient of relationship. The inbreeding coefficient is used as a measure of consanguinity. The coefficient corresponds to the probability that two alleles (a variant of a given gene) in the DNA were inherited from the same individual. The Coefficient of Relationship (CR) measures the consanguinity between two individuals. It has been defined as being twice the inbreeding coefficient that would have a child of the two individuals.
The representation clarifies that each of our family trees does not have consanguinity in the first five generations. We have created an interactive tool to support the exploratory analysis of consanguinity in family trees.
The following figure shows my family tree with six generations.
It becomes clear that my parents do not have any kinship between them. My paternal grandparents are third cousins once removed, as indicated by the orange label. The term 'once-removed' means that they are separated by one generation. The horizontal arc represented is a clear indication of that. My grandfather José Luís Travassos Valdez de Moura Borges has four generations between him and their common ancestors, António Borges and Maria Fonseca, while my grandmother, Maria da Assunção Nunes de Moura, has five generations.
The following plot shows the six generations tree centered on my father. It reveals that José Valdez, in generation 3, has a pretty high consanguinity. His father, José Lúcio Travassos Valdez, the 1st Count of Bonfim, married with Jerónima Emília Godinho Valdez, who was his double first cousin. Double first cousins arise when two siblings reproduce with another set of siblings.
The problems associated with high consanguinity in marriages are well known. When discussing the Contextual Family Tree, we have seen that this couple had ten children, but only two of them had offspring. A closer look at the records shows that the elder son had ten children while the other child with offspring had three children, but two died at six years old.
The representation for consanguinity analysis can be set for any number of generations, but the plot becomes cluttered when we increase it too much. The following plot shows my father's tree for ten generations. It provides a nice overview of the consanguinity in his ancestry, and the interactive features of the tool provide the means to explore particular sections of the tree.
The following video illustrates how to use the VisAC tool:
This work is published in the Information Visualization Journal, and it is available on Github an R package that runs the VisAC interactive tool.
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