Cousin Marriage F Coefficient Lookup

Bounded offline reference: Conventional offspring inbreeding coefficients depend on pedigree paths and shared ancestors, not cousin labels alone. Source: Population genetics pedigree theory. Bounded simple unrelated-founder pedigree examples, not medical/genetic risk prediction. Only explicit topic keys supported: firstCousins, secondCousins, firstCousinsOnceRemoved, limitations. No complete external corpus, live data or personal assessment implied.

Description

A pedigree inbreeding coefficient describes expected identity by descent under declared ancestry assumptions.

A pedigree inbreeding coefficient describes expected identity by descent under declared ancestry assumptions.^[1]

A simple cousin relationship does not identify additional shared ancestry or provide a clinical risk estimate.

When to use Cousin Marriage F Coefficient Lookup

Use this tool to read a bounded explanation for an exact reference topic. Establish the population, period, variable definitions, sample coverage and independently applicable instrument or calibration.

How to use Cousin Marriage F Coefficient Lookup and understand its results

Establish the population, period, variable definitions, sample coverage and independently applicable instrument or calibration.
Enter topic, using the field meanings and rules below, then run the tool.
Read result.text for the exact topic token. Consult the limitations entry where available before applying the reference to your actual context.
Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.

Input field	Meaning	Value type	Requirement
topic	Topic	string	Required

Choose one exact topic token from the table. The implementation looks up the stored value and returns it in the documented output field. Matching is case-sensitive; unrecognized tokens fail. This is an offline bounded reference, not a live catalogue or independent attribution.

Topic token	Stored value
firstCousins	For ordinary first-cousin parents with unrelated non-inbred founders, F=1/16in the simple pedigree.
secondCousins	For ordinary second-cousin parents under the same assumptions, F=1/64.
firstCousinsOnceRemoved	For first cousins once removed under the same assumptions, F=1/32.
limitations	Additional shared ancestry, inbred founders and multiple paths alter F; no diagnosis or marriage advice.

value=referenceTable[exactToken]

Use the matching field units and the exact boundary, ordering and reference rules above.

Output field	Meaning	Value type
result	Calculated observation or qualified reference	object
result.text	Stored explanation for the exact selected reference token.	string

json

{
  "input": {
    "topic": "firstCousins"
  },
  "output": {
    "result": {
      "text": "For ordinary first-cousin parents with unrelated non-inbred founders, F=1/16in the simple pedigree."
    }
  }
}

Limitations and assumptions

Population definitions, survey design, calibration and observation coverage are independently established. A result describes the supplied record or conditional model without demonstrating causation, validating an instrument or supplying representative population evidence. Additional shared ancestry, inbred founders and multiple paths alter F; no diagnosis or marriage advice.

Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Extremely large composite outputs are rejected.

Alternative or Complementary methods

For a related step, use Assortative Mating Correlation Calculator: Assortative-mating correlation describes a linear association between matched partner scores. For a complementary comparison, use Intermarriage Rate Calculator: Intermarriage rate counts unions crossing a declared category boundary.

References

Cousin Marriage F Coefficient Lookup — tool.io

Similar or alternative tools

Assortative Mating Correlation Calculator
Assortative-mating correlation describes a linear association between matched partner scores.
Intermarriage Rate Calculator
Intermarriage rate counts unions crossing a declared category boundary.