His father was John Bentinck, a captain in the navy, and his mother was Renira van Tuyll van Serooskerken.
John's mother and thus William's grandmother was Charlotte Sophie of Aldenburg, the ruler of Aldenburg 1738–1748.
She was the cousin to the mother of Catherine the Great and had good connections to the Russian court.
Probably William also had a good relation with Duke George of Oldenburg who was referred to as a prince in Russia.

He married Frances Augusta Pierrepont in 1802 and together they had eight children, but only four survived to adult age.
His oldest son George Bentinck (1803–1886) became an MP.
His father was John Bentinck, a captain in the navy, and his mother was Renira van Tuyll van Serooskerken. John's mother and thus William's grandmother was Charlotte Sophie of Aldenburg, the ruler of Aldenburg 1738–1748. She was the cousin to the mother of Catherine the Great and had good connections to the Russian court. Probably William also had a good relation with Duke George of Oldenburg who was referred to as a prince in Russia.
He married Frances Augusta Pierrepont in 1802 and together they had eight children, but only four survived to adult age. His oldest son George Bentinck (1803–1886) became an MP.
William Bentinck (Royal Navy officer)