Thutmose I was probably a commoner by birth; in any case he does not lay claim to any royal blood.
He succeeded to the throne when Amenhotep I died childless, perhaps partly because of his association
with the royal family by marriage (the Egyptians did not have any version of the Salic law).
He had a wife called
Mutnofret, who bore the title King's Daughter. It is known that Mutnofret bore three or four sons,
all of whom appear to have died as young children except the one who eventually became Thutmose II.
Apparently, Mutnofret was not the wife of Thutmose I during his kingship, otherwise she would also appear
in carvings with the title "King's Wife" and even "God's Wife of Amon", which she never does.

It is only too likely that she died before Thutmose' accession to the throne,
which occurred at an unusually advanced age; Thutmose I died at about fifty, which is
an immense life-span for an ancient Egyptian (those who survived till fourteen could expect,
on the average, to reach age thirty...)

Upon becoming king, or at least heir apparent, Thutmose married a woman called Ahmose. Ahmose is often given
the title of "King's Sister" (senet nesu) , for which it has been thought that she was the sister of Amenhotep I,
and that Thutmose married her in order to consolidate his succession to that king.
However, she never appears with the more honorable title of "King's Daughter" (sat nesu).
This may mean that she was not the sister of Amenhotep, but of Thutmose himself.
Such incestuous marriages were frequent in the royal dynasty, but very rare outside, so if this is the case,
it would probably mean that Thutmose married Ahmose after his promotion to heir apparent (or perhaps even co-regent).

Marriages with sisters and even daughters occurred with most extraordinary frequency among the kings and queens of the 18th dynasty.

Thutmose and Ahmose had one daughter, Hatshepsut, and perhaps another daughter Neferubiti,
who is only ephemerally mentioned and may have died very young.

Thutmose was chosen as successor to Amenhotep because he was an able and proven general. Apparently, his
accession was not considered the beginning of a new dynasty. During his reign, he continued to persecute the Hyksos,
chasing them farther away and reaching the River Euphrates, where he proudly left a commemorative stela.

In fact, he crossed the Euphrates and entered Naharin, the territory controlled by Egypt's new enemy -

                                                            the King of Mitanni.

The ubiquitous Ahmose son of Ibana says of this:

His Majesty went to Retenu to vent his wrath throughout foreign lands.
His Majesty arrived at Naharin. His Majesty - life, prosperity and health be upon him -
found that the enemy was gathering troops. Then his Majesty made a great heap of corpses
among them. Countless were the living captives of his Majesty from his victories. Lo, I was
at the head of the army and his Majesty saw my bravery. I brought away a chariot, its horse,
and the one who was upon it as a living captive to present to is Majesty.
I was rewarded with gold yet again.

Thutmose is also marvelously remembered for his idea of Biban el-Muluk,
the Valley of the Gates of the Kings, known as Valley of the Kings.
Because of the ever-present danger of tomb robbers, he decided to
separate the tombs of the royal family from their mortuary temples,
and to conceal them invisibly in a hidden valley.
He named his chief architect Ineni to supervise this job: