In Nigeria's southwestern city of Igbo-Ora, there is an unusually abundant number of twins - so much so that it is the west African nation's self-proclaimed "twin capital". 

"Nearly every family here has twins or other multiple births," says local chief Jimoh Titiloye.

For the past 12 years, the community has organised an annual 'Twin Festival', where twins from Igbo-Ora and elsewhere gather to celebrate their existence.

This year's event, held earlier this month, included more than 1,000 pairs of twins and drew participants from as far away as France, organisers said.

Why are there so many twins in Igbo-Ora?

There is no proven scientific explanation for the high rate of twins in Igbo-Ora, a city of at least 200,000 people 135 kilometers (83 miles) south of Nigeria’s largest city, Lagos.

However, many in Igbo-Ora believe it can be traced to women's diets.

Alake Olawunmi, a mother of twins, attributes it to a local delicacy called amala which is made from yam flour.

John Ofem, a gynecologist based in the capital, Abuja, says it very well could be “that there are things they eat there that have a high level of certain hormones that now result in what we call multiple ovulation.”

While that could explain the higher-than-normal rate of fraternal twins in Igbo-Ora, the city also has a significant number of identical twins. Those result instead from a single fertilised egg that divides into two - not because of hyper-ovulation.

Feast your eyes on snaps of this year's Twin Festival: