If you believe the age old saying "opposites attract" you may want to re-think your decision.
Despite the expression, people are more likely to be attracted who individuals who look like themselves or their parents.
Scientists have already established several species including birds, mammals, and fish mate with animals that resemble their parents, which is otherwise known as sexual imprinting.
For example, if a baby goat is raised by a sheep, when the goat reaches sexual maturity, it will look for another sheep to mate with, as opposed to its own species.
According to Psychology Today, this may signify that "our incest taboos are social constructs instituted to prevent people from following their instincts."
Researchers at the deCODE genetics company in Reykjavik, Iceland have found that marriages between third or fourth cousins is more optimal for reproduction purposes, as they are likely to have more children and grandchildren compared to unrelated couples. They suggested while romantic relationships between siblings and first-cousins may lead to inbreeding, third or fourth cousins have just enough genetic similarity where their offspring may be produced from the best gene pool.
This theory goes against the "Westermarck effect," which argues people who grow up together won't be attracted to each other when they reach sexual maturity.
Studies conducted by Finnish anthropologist Edvard Westermark are aligned to recent findings, which suggest living in close proximity to another person is the decisive factor for desensitization in terms of sexual attraction - opposed to degree of their resemblance.
However, Psychological Science reports we only perceive people to look similar to us once we deem them trustworthy.
While it might seem doubtful, researchers at Department of Psychology at Royal Holloway University in England conducted an experiment where people were shown images of various percentages of their face morphed with one of two other people. They were asked to decide if the image looked more like them or one of the others.
Following the experiment, the participant took part in bargaining games with the two confederates. One of the individuals reciprocated trust, while the other did not.
After the game, they were asked to identify the pictures again, where it was discovered the participants judged the more trustworthy player was more physically similar to them compared to the deceitful player.
"Recent studies show that when a person looks similar to ourselves, we automatically believe they are trustworthy. Here we show for the first time that the reverse is also true. When a person is shown to be more trustworthy, it can lead us to perceive that person as looking more similar to ourselves," researcher Harry Farmer said.
The experiment leads the researchers to believe the results have the potential to hold significant implications for social relationships.
Lead author Professor Manos Tsakiris said: "Our results show how our perceptions of similarity between us and others extend beyond objective physical characteristics, into the specific nature of social interactions that we have."
"It may be that our experience of facial similarity tracks information about genetic relatedness. If so, our results suggest that evidence of trust in others also serves as a cue to kinship," co-author Ryan McKay added.
Do you think your significant other looks like you or your parents?