It's 2018 and yet in many Arab countries "cousin marriages" or marrying a close relative is still a thing.

To many, consanguineous marriages are considered part of tradition and in some Arab societies, marrying a first or second cousin is often a non-negotiable matter.

Earlier this week, people across the region debated the divisive issue yet again via the viral hashtag: "Marrying relatives."

Here's how the discussion played out online:

It all started when this hashtag went viral

"Marrying relatives." 

It then sparked a heated debate on Twitter

Some said they were all for marrying a relative

"Sometimes a relative is better than a stranger. I think such marriages can be successful." 

Some shared their own positive "cousin marriage" experiences

"I married my cousin and we're happily married. We have three children, Mohammad, Salem and Naneese... you want to be happy? Marry a relative." 

However, many were completely against the cultural phenomenon

And shared statistics to back up their points of view

"After working as a genetic disorder specialist for 12 years, the statistics found in my clinic and by colleagues in my department reveal that 80% of people who suffer from genetic disorders are children of people who married close relatives." 

"Marrying a relative can cause problems between two families"

Marrying a relative? No thanks

A few just can't comprehend the concept

Mood ...

Others summed it all up using two words

Percentages of "cousin marriages" are high in many Arab countries

Marriages between relatives have been common in Arab societies for centuries. 

According to research conducted by the Dubai-based Centre for Arab Genomic Studies, "at least half of all Gulf Arab marriages are between cousins." 

Intermarriages are also widespread in the rural areas of countries including Lebanon, Egypt, and Jordan. 

These unions often lead to the passing of serious and rare genetic diseases to children. 

In recent years, pre-marital screening for specific genetic diseases became mandatory in several Arab countries and scientists hope this will bring a halt to the "cousin marriage" phenomenon.