On 07 Dec 1646 [his father] Frederick William "Great Elector" Hohenzollern Elector Brandenburg (age 26) and [his mother] Luise Henriette Orange Nassau (age 19) were married at The Hague. They were half first cousin once removed.

On 13 Jun 1668 [his father] Frederick William "Great Elector" Hohenzollern Elector Brandenburg (age 48) and [his step-mother] Sophia Dorothea Oldenburg (age 31) were married.

Before 1680 Frederick I King Prussia (age 22) and Elisabeth Henriëtte Hesse-Kassel (age 18) were married. She the daughter of Wilhelm "The Just" VI Hesse-Kassel and Hedwig Sophia Hohenzollern (age 56). He the son of Frederick William "Great Elector" Hohenzollern Elector Brandenburg (age 59) and Luise Henriette Orange Nassau. They were first cousins.

Before 1685 Frederick I King Prussia (age 27) and Sophia Charlotte Hanover Queen Consort Prussia (age 16) were married. She the daughter of Ernest Augustus Hanover Elector Brunswick-Lüneburg (age 55) and Sophia Palatinate Simmern (age 54). He the son of Frederick William "Great Elector" Hohenzollern Elector Brandenburg (age 64) and Luise Henriette Orange Nassau. They were second cousins. She a great granddaughter of King James I of England and Ireland and VI of Scotland.

In 1700 [his son-in-law] Frederick I King Sweden (age 23) and [his daughter] Louise Dorothea Hohenzollern (age 19) were married. She the daughter of Frederick I King Prussia (age 42) and Elisabeth Henriëtte Hesse-Kassel. He the son of Charles I Landgrave Hesse-Kassel (age 45) and Maria Amalia of Courland Landgravine Hesse-Kassel (age 46). They were first cousins.

In 1701 Johan Adolf Von Kielmansegg (age 32) and [his illegitimate sister-in-law] Sophia Charlotte Hanover Countess of Darlington and Leinster (age 26) were married. She the illegitmate daughter of Ernest Augustus Hanover Elector Brunswick-Lüneburg.

On 28 Nov 1706 [his son] Frederick William "Soldier King" I King Prussia (age 18) and [his daughter-in-law] Sophia Dorothea Hanover Queen Consort Prussia (age 19) were married. She the daughter of King George I of Great Britain and Ireland (age 46) and Sophia Dorothea Hanover Queen Consort England (age 40). He the son of Frederick I King Prussia (age 49) and Sophia Charlotte Hanover Queen Consort Prussia. They were first cousins. He a great x 2 grandson of King James I of England and Ireland and VI of Scotland.

In 1708 Frederick I King Prussia (age 50) and Sophia Louise Mecklenburg-Schwerin Queen Consort Prussia (age 22) were married. She by marriage Queen Consort Prussia. The difference in their ages was 27 years. He the son of Frederick William "Great Elector" Hohenzollern Elector Brandenburg and Luise Henriette Orange Nassau. They were fourth cousins.