0:00 so the probability that a full sip that

0:03 is your brother or sister they're not

0:05 identical twins has a given genotype for

0:09 a homozygote is one plus the allele

0:11 frequency of whatever that allele is

0:13 squared over four and then the

0:17 heterozygotes are what you see there for

0:19 two alleles so that's how the paternity

0:24 calculations work you know it's give or

0:27 take it's around a quarter for locus and

0:30 k is the number of low size so the

0:32 probability that two full siblings have

0:35 a given genotype that's two Leal's

0:39 is 1/4 to the K K being the number of

0:43 low site because the probability that

0:46 they have one allele is what from one

0:49 parent right get one from one chromosome

0:55 or the other right probability that they

0:57 have an allele from the other parent is

0:59 yeah what's probability that they have

1:01 both 1/2 times 1/2 so for a genotype

1:06 that's two alleles 1/4 to the K okay

1:12 being the number of low site

1:14 you can see that when you get to 13 the

1:18 probability that two full sibs are gonna

1:20 have same genotype across 13 lows I know

1:26 you know you're assuming that parents

1:29 are heterozygous too right

1:31 so parents are homozygous then the

1:34 probability of getting it is not it's 1

1:38 but on average you could even multiply

1:42 that by 0.8 because 80% heterozygosity

1:44 right still gonna be pretty small one in

1:50 that's like almost 80 million you follow

1:54 me so these systems can even

1:58 discriminate amongst first-degree

2:01 relatives pretty well you have enough

2:04 low side maybe one low because you may

2:05 not be able to just depends on the

2:07 genotypes but over 13 you're getting

2:10 enough genetic information to

2:11 discriminate between them