President met Auma Obama as he landed in Nairobi late Friday night
Was also greeted by Kenyan president Uhuru Kenyatta and other officials
Was whisked into capital city in a motorcade ahead on five-day Africa visit
Went to family meal in his Nairobi hotel and sat next to step-grandmother
Obama will also visit Ethiopia after three days in Kenya
President Barack Obama was all smiles on Friday evening as he sat down for dinner with Kenyan relatives on a state visit to the country's capital.
Not long after touching down in Nairobi, Obama was taken to a hotel where he met fellow Obamas including his half-sister and step-grandmother.
The President was seen smiling at a table between Mama Sarah Obama, whom he calls 'granny', and Auma Obama, who was born to his father's first wife.
Some three-dozen people were at the meal sitting round the President at the Villa Rosa Kempinski hotel, where he is staying on his brief visit to the country.
The luxury property can accommodate some 500 diners and has a host of restaurants as well as a plush presidential suite on its tenth floor.
He headed straight to the family occasion after disembarking from Air Force One late Friday night, where he was met by Auma as well as a group of high-ranking Kenyan officials.
Included among them were president Uhuru Kenyatta, who joked with Obama as he sat at a desk rolled up in front of the presidential plane and signed a visitors' book for the nation.
Crowds of excited citizens crowded as close as possible to his heavily-guarded route and welcome him to their country.
Hours before Obama's arrival, police blocked major roads and emptied streets of traffic in the usually congested capital as part of a huge security operation.
Kenya is a vital ally of the West in the battle against the Somali Islamist group al Shabaab, and Obama is likely to focus talks in Nairobi on security cooperation.
The al Qaeda-linked group was behind an attack on Nairobi's upscale Westgate shopping center in 2013, killing at least 67 people, as well as an attack in April at a Kenyan university near the Somali border that left 148 people dead.
In Nairobi, Obama will preside at a Global Entrepreneurship Summit, pay tribute to victims and survivors of the 1998 U.S. embassy bombing and dine with Kenyatta, whose indictment by the International Criminal Court for crimes against humanity largely barred Obama from visiting sooner. Charges have been dropped.
Deputy President William Ruto, still facing similar charges in The Hague-based court, was not at the airport reception ceremony. He denies having had a role in fomenting violence after the disputed 2007 election.
In the year before that vote, Obama visited Kenya when he was still a senator.
On this trip as president, he is not expected to travel to the village most closely associated with the family name and where his father is buried.