A young woman entered Damian Haskell’s law office, quite beside herself. “You ha

Question

A young woman entered Damian Haskell’s law office, quite beside herself. “You have to help me keep my children,” Lillian said. “They don’t believe they’re mine.” “The court is threatening to take your children away?” Damian asked. “Yes, they’re my children.” “Is this a divorce? Why is the court trying to take your children?” “No! My boyfriend and I are separated, but he doesn’t want custody. I applied for welfare, and the judge said they’re not my kids.” “Ma’am, are your children adopted?” “No! They’re mine. I’m their mother! I gave birth to them. But the court says DNA proves I’m not their mother.” Damian paused for a moment, then replied. “Your DNA doesn’t match your children?” “The test says it doesn’t, but I am. They keep asking me ‘Who’s their real mother?’ ‘Where did you get them?’ I got them from me!! How can I give birth to someone else’s child?” “Did they test you again?” “Yes, but the tests must be wrong. They’re my kids.” “Ma’am, I’m sorry but DNA evidence is very hard to contest in court.” “Every darn lawyer I call says that,” she said with anger in her voice. “I gave birth to them. I’m their mother! The tests must be wrong.” Damian didn’t answer immediately. But for some reason, he decided he could afford to continue the conversation even though challenging DNA evidence did not seem to be a good way to develop his reputation as a successful lawyer, especially if the re-tests gave the same result. Welfare cases generally didn’t help the bottom line either. “Tell me what happened.” Damian reached for his notebook and prepared to listen. Lillian had applied for welfare after separating from her longtime boyfriend, Dwayne. Per state law, the DNA of her two children was compared to Lillian’s DNA and Dwayne’s DNA to establish paternity. The law was intended to prevent welfare money being spent on children whose fathers could pay. Probably no one had ever thought of the test being a maternity test. The tests revealed each child shared roughly half of their DNA markers with their father, which Damian knew was the expected contribution of a father to his children’s DNA. If Damian’s knowledge was correct, the other half of the DNA should be from Lillian. But the children’s DNA did not match Lillian’s. According to Lillian, the tests showed that about a quarter of each child’s DNA matched her DNA. She said welfare people kept asking her if they were her sister’s children, or her daughter’s, but she didn’t have a sister and being only 22 she couldn’t understand why the welfare agent thought she could be the kids’ grandmother. They also asked whether she had undergone in vitro fertilization (IVF), or had acted as a surrogate mother for someone else. Lillian denied both. According to Lillian, she and Dwayne had conceived the children (now 2 and 3 ½ years old), and she had given birth to them in a hospital with no complications. She had the birth certificates and medical records to prove it. Damian’s head was spinning. The birth certificates and medical records were authentic, and Lillian’s distress was genuine. He really wanted to believe her story, but he needed to talk to someone about the biology of reproduction to see if there was any way a child could not get his mother’s DNA. 3) [20 points] The welfare people asked Lillian a number of questions about where she got the children from. From their questions, it is clear they had formed several hypotheses as to why Lillian’s DNA was only a 25% match to the DNA of her children: a) that the children actually belonged to her sister; b) that the children actually belonged to her daughter; c) that she had acted as a surrogate for someone else; d) that she had undergone in vitro fertilization For each hypothesis, explain how the child in question would be a 25% match to Lillian’s DNA (Hint: for parts c and d, there are some important assumptions about the source of the donor egg or embryo that must be true in order for Lillian to be a 25% match! Please be specific.)

Explanation / Answer

a)

Suppose the children belonged to her sister. The sister inherited DNA from the same parents from which the Lillian inherited her DNA. Now, Lillian’s sister’s children will have 50% DNA of their mother (i.e. Lillian’s sister) and the rest 50% DNA of their father (Damian). This DNA should be 25% match of their aunt i.e. Lillian.

b) Similarly the DNA of grandchildren is a 25% match of the grandparents. So, if Lillian was the grandmother of the children, then there can be a 25% similarity in the DNA.

c) Surrogate mother is when a female donates her womb to somebody else’s ova. In this oocytes of some other female are harvested (may be Lillian’s sister). Then these could be fertilized with the sperms of Damian in a specialized dish in the laboratory. At the four-cell stage, two embryos were transferred to Lillian. After 5 weeks ultrasonography was done. A fetus was seen; the mother of this fetus was Lillian’s sister; it couldn’t be Lillian because the ova did not belong to her and the father was Damian.

d) In in-vitro fertilization (IVF) the above said process occurs. The oocytes of the female are harvested and made to fertilize with the sperms of anonymous donors (Damian in this case).

Note that the children can be chimeras. This probability has been ignored by the officials in Lillian’s case. Most probably blood cells are being tested for the DNA test. If further blood is tested for DNA, then presence of chimeras can be revealed.

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