Discussion:
Paternity Testing
This question tests your achievement of Cognitive skill CS2 (part (a)) and Practical and Professional skill PS1 (part (b)).
John and George are brothers. They both claim to be the father of Child A and of Child B. The children are definitely siblings; they have the same mother.
(i) From the data in Table, what is the sex of Child A and of Child B. State how you came to your conclusions.
(ii) Briefly explain how the alleles that make up the genotype of a child at each locus compare to the alleles in his or her parents' genotypes.
(iii) By analysing the SGM + profiles in Table 2, say which one of the statements 1-4 below is most likely to be true. Explain your answer fully. You should explain any evidence that rules out John or George from being the father of Child A or Child B. (Hint: a good way to tackle the question is to look at the DNA profile of one potential parent, John for example, and then, individually, compare his profile with first Child A and then Child B. Then do the same for the other potential parent. This complete analysis will allow you to answer the question fully.)
1 John is the father of both children.
2 George is the father of both children.
3 John is the parent of one child and George the parent of the other child.
4 Both John and George could be the father of both children.
|
Locus
|
Child a
|
Child b
|
John
|
George
|
|
D3S1358
|
18.19
|
14,16
|
14,18
|
16,18
|
|
vWA
|
15,21
|
15,21
|
17,21
|
17,21
|
|
D16S539
|
11,12
|
11,13
|
12,12
|
12,13
|
|
D2S1338
|
18,23
|
18,24
|
18,23
|
23,24
|
|
D8S1179
|
12,13
|
12,14
|
15,15
|
12,12
|
|
D21S11
|
29.2,32.2
|
29,31.2129,31.2
|
29,31.2
|
29,31.2
|
|
D18S51
|
13,14
|
13,14
|
12,16
|
14,14
|
|
D19S433
|
13,15
|
13,14
|
12,15
|
14,15
|
|
THO1
|
9,9
|
19,23
|
25,25
|
19,24
|
|
FGA
|
19,22
|
19,23
|
25,25
|
19,24
|
|
amelogenin
|
XY
|
XX
|
XY
|
XY
|