Twin studies and adoption studies | Behavior | MCAT | Khan Academy 

YOOO SHE REALLY DOES WTF

Even the science part

True

🤣😂🤣

I don't think any siblings share the exact same environment. The eldest child experiences a period of time as an only child, for example, whilst none of its siblings do. Not even twins experience the same environment. For example, it is well documented that twins often receive differing levels of nutrition whilst in the womb. After birth their individual environments are likely to diverge further. One might be regularly wrapped in a thinner blanket and have to put more energy towards keeping warm. They may show different food preferences and so, eat different things. They might be separated into different classes at school and as a result experience different teaching styles or one might be bullied in class whilst the other isn't. One might have his/her first love reciprocated whilst the other might experience rejection, etc, etc, etc.

Chen Boi oh well. 😁😁😁😁😁😁

In twin method, both the twins are studied in a single environment as a unit. In co-twin, both are separated and the effect of "nurture" (different environments) is studied on them. That's why it's also called nature vs nurture study method.

"50%" is a statistical estimation. You may also look at my comment above.

They share 50% of genes "on average". It's a question pertaining to statistics: "average/ mean value/ theoretical normal distribution of something"...

Alex Fan - Let's look at a single gene. Your father has two copies of that gene (one received from each of his parents). He will pass just one copy of the gene onto you. He will also pass one copy onto your siblings. Which copy he passes onto you and which copy he passes onto your siblings is determined by chance and occurs completely independently of one another. Therefore, the likelihood that you and any one of your siblings will both receive the same copy of that gene from your father is 50%. The same is true for your mother. You therefore have two copies of the gene, one received from your father and one received from your mother. You and any one of your siblings might, through chance, receive the same copy of this gene from both your father and your mother, in which case you would be genetically identical for that gene. Alternatively, you and any one of your siblings might receive the same copy of the gene from one parent, but different copies of the gene from your other parent. In this case, you and your sibling would be 50% genetically identical for that gene. The final scenario would see you and any one of your siblings receiving a different copy of the gene from both of your parents, in which case you'd be genetically different at that gene (i.e. 0% similarity). So for any given gene, you might end up 100%, 50%, or 0% identical to your sibling. Since this process is random (i.e. occurs through chance events), all three outcomes have an equal chance of occurring. So, when we consider all of the genes (and non-genes) that make up your entire genome, you and your sibling will have received, on average, the same gene copies from your parents on 50% of occasions. There are some other factors that complicate things, but this is the general model used.

@@TrentRidley Just to verify my concept: this 50% is for a “particular” gene, right? But we have many more genes which will make all the siblings overall traits (set of all the traits ) statistically very different from one another, isn’t it? Is it due to the fact that 23 chromosomes that are passed from WITHIN one parent can vary randomly (any combination of 23 chromosomes of grandparents)?

Anastasia Levchenko not that I don't believe your random comment, without any backup, but do you have any credibility?

MZ twins share 100% of their genetic material, but genes may be expressed differently due to epigenetics determining gene expression.

angelface635 - What Anastasia has outlined is well supported by scientific evidence and is not controversial within the field of biology. Here's a short video explaining epigenetics.... ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-_aAhcNjmvhc.html Rebecca Sorum - Whilst MZ twins start out being 100% genetically identical, they are unlikely to remain as such due to the accumulation of different chance mutations within each individual. Any impact these mutations have will depend upon which genes they occur in and to what extent, if any, they impact gene expression and/or the gene products. Regardless, I think any differences we can detect in the phenotypes of MZ twins are largely due to environmental factors. The idea that twins share the exact same environment is also incorrect. Even whilst in the womb their individual environments can vary. For example, it is a well documented phenomenon that one twin often receives more nutrients through the placenta than its sibling. After birth, their individual environments will diverge further - one might eat more than the other, they might eat different things because they have a preference for different foods, as babies one might be routinely wrapped in a thinner blanket resulting in a slightly lower body temperature, they might be separated into different classes at school and thus experience different teaching styles or one might by bullied by their class mates and the other accepted, for one their first love might be reciprocated whilst the other might experience rejection, etc, etc.

@@TrentRidley that being said, identical twins are as close genetically as it is possible to be.

Turn up the volume

I could hear perfectly

Ayanna Brooks which part?